Tungsten (W) films are deposited as a blanket layer using chemical vapor deposition (CVD) techniques during semiconductor manufacturing. The tungsten can be deposited through a chemical reduction of tungsten hexafluoride (WF.sub.6) using a hydrogen (H.sub.2) or silane (SiH.sub.4). Usually, the tungsten is deposited at temperatures ranging from 425.degree. C. to as high as 475.degree. C., such as disclosed in the upper range of temperatures in U.S. Pat. No. 5,795,824. In this prior art process, tungsten film is grown on a semiconductor substrate by positioning the semiconductor substrate within a chemical vapor deposition chamber having a number of different pedestals that are heated. Initiation gases, such as hydrogen and silane, are provided to initiate a growth at temperature ranges of 350 to 475.degree. C., followed by nucleation with a gas flow that replaces the initiation gases, where tungsten film is formed at a rate in excess of approximately 100 NM/MIN on the surface. The hydrogen and silane gas flow occurs without argon gas at a first pedestal. The substrate is repositioned at a second deposition station or pedestal within the deposition chamber, followed by successive positioning at other pedestals.
However, the current chemical vapor deposition tungsten processes are not adaptable for use with low-K dielectrics because the stability of dielectrics are compromised by the high tungsten deposition temperatures of 425 to 450.degree. C. Thus, those processes that can be used with these higher temperatures are not adaptable for use with the low-K dielectrics requiring low temperature applications. It is difficult to fabricate any chemical vapor deposition tungsten plugs at temperatures around 375.degree. C. without extensive hardware modifications. More optimal gas species combinations, gas flows and gas flow sequences are required in the chemical vapor deposition chambers, such that a low resistivity, high reflectivity, and smaller grain size tungsten plug could be obtained at the lower temperatures compared to the prior art using the 425 to 450.degree. C. range. It would also be advantageous if there could be little hardware changes to existing chemical vapor deposition chambers. Instead, changes in the gas flow and gas species combinations and gas flow sequences are the better design choice.